Glucose-induced structural changes and anomalous diffusion of elastin

Elastin is the principal protein component of elastic fiber, which renders essential elasticity to connective tissues and organs. Here, we adopted a multi-technique approach to study the transport, viscoelastic, and structural properties of elastin exposed to various glucose concentrations (X=[gluc]/[elastin]). Laser light scattering experiments revealed an anomalous behavior (anomaly exponent, beta < 0.6) of elastin. In this regime ( beta < 0.6), the diffusion constant decreases by 40% in the presence of glucose (X > 10), which suggests the structural change in elastin. We have observed a peculiar inverse temperature transition of elastin protein, which is a measure of structural change, at 40 degrees C through rheology experiments. Moreover, we observe its shift towards lower temperature with a higher X. FTIR revealed that the presence of glucose (X < 10) favors the formation of beta-sheet structure in elastin. However, for X > 10, dominative crowding effect reduces the mobility of protein and favors the increase in beta-turns and gamma-turns by 25 +/- 1% over the beta-sheet (beta-sheet decreases by 12 +/- 0.8%) and alpha-helix (alpha-helix decreases by 13 +/- 0.8%). The stiffness of protein is estimated through Flory characteristic ratio, C-infinity and found to be increasing with X. These glucose-based structural changes in the elastin may explain the role of glucose in age-related issues of the skin.